Soak 2 tablespoons of rice in water for 30 minutes, then drain and rinse well.
In a bowl, mix the 500g minced meat with the drained rice, 1 slice of bread, 2 eggs, and 1 finely chopped onion until smooth. Season with salt and pepper.
Form the mixture into nut-sized dumplings and refrigerate until ready to cook.
In a large pot on medium heat, cook the coarsely grated carrots, second finely chopped onion, parsley roots, celery, and diced bell pepper for 10 minutes, stirring occasionally.
Add the white cabbage leaves and peeled tomatoes to the pot.
Pour in 2 liters of water and add the chopped dill. Bring to a boil, then reduce heat to medium-low and simmer for 1 hour 30 minutes.
Gently add the dumplings to the hot soup and bring back to a boil. Reduce heat to medium-low and simmer until the dumplings float to the surface, roughly 15-20 minutes.
Add the sour cabbage soup to adjust acidity and taste. Season with salt and pepper as needed.
Stir in the freshly chopped parsley and serve hot.